1. Field of the Invention
The present invention relates to an electromagnetic component, and more particularly to a compact electromagnetic component and a multilayer winding thereof having two forms of multiple metal rings.
2. Description of Related Art
Electromagnetic components may be an inductor, a choke, a transformer or the like and has a coil. A conventional method of fabricating the coil is winding an enamel wire around a core. However, the electromagnetic component fabricated by winding has many limitations.
1. The size of the electromagnetic component is difficult to reduce and to provide a large power requires a large diameter enamel wire, large power electromagnetic components are bulky.
2. The electromagnetic component is not easily fabricated by automatic process so retaining high manufacturing costs.
Based on the above, a compact electromagnetic component is proposed. With reference to FIG. 13, a conventional folded foil transformer (90) construction has a primary winding (91) and a secondary winding (92).
The primary winding (91) is formed from a length of foil preferably wrapped in insulation and has a generally rectangular-shape with long planar segments (911), short planar segments (912) and corner turns defining a rectangular-shaped shaft. The secondary winding (92) has multiple U-shaped conductive sheets. The secondary segments (921) are preferably positioned adjacent to long planar segments (911) of the primary winding (91). Therefore, the electromagnetic component has low profile. However, since the primary winding (91) is fabricated by wrapping the length of foil, the corner turns are relatively weak.
With further reference to FIGS. 14 and 15A to 15C, another conventional compact electromagnetic component (90a) has a bobbin (93), a first annular winding pattern (941), a second annular winding pattern (942) and a semicircular winding pattern (943). The first annular winding pattern (941) has two connecting protrusions (941a, 941b) respectively having an enclosed and open mount and a first sector cutout (a). The second annular winding pattern (942) has two enclosed connecting protrusions (942a) and a second sector cutout (β). The semicircular winding pattern (943) has two enclosed connecting protrusions (943a, 943b). The bobbin (94) has multiple pins (941) corresponding to the connecting protrusions (941a, 941b) (942a, 942b) of the winding patterns (941, 942, 943). Therefore, the winding patterns (941, 942, 943) can be stacked on the bobbin (93). However, three different winding patterns must be fabricated by different molds and processes so has high manufacturing costs.
To overcome the shortcomings, the present invention provides a multilayer compact electromagnetic component to mitigate or obviate the aforementioned problems.